linux-kernel - Re: [PATCH] sched: prefer an idle cpu vs an idle sibling for BALANCE

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Message-ID: <55663113.40407@redhat.com>
Date:	Wed, 27 May 2015 17:03:15 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Josef Bacik <jbacik@...com>, mingo@...hat.com,
	peterz@...radead.org, linux-kernel@...r.kernel.org,
	kernel-team@...com
Subject: Re: [PATCH] sched: prefer an idle cpu vs an idle sibling for BALANCE_WAKE

On 05/27/2015 04:09 PM, Josef Bacik wrote:
> On 05/26/2015 05:31 PM, Josef Bacik wrote:

>> SD_BALANCE_WAKE is supposed to find us an idle cpu to run on, however
>> it is just
>> looking for an idle sibling, preferring affinity over all else.  This
>> is not
>> helpful in all cases, and SD_BALANCE_WAKE's job is to find us an idle
>> cpu, not
>> garuntee affinity.  Fix this by first trying to find an idle sibling,
>> and then
>> if the cpu is not idle fall through to the logic to find an idle cpu. 
>> With this
>> patch we get slightly better performance than with our forward port of
>> SD_WAKE_IDLE.  Thanks,
>>
> 
> I rigged up a test script to run the perf bench sched tests and give me
> the numbers.  Here are the numbers
> 
> 4.0
> 
> Messaging: 56.934 Total runtime in seconds
> Pipe: 105620.762 ops/sec
> 
> 4.0 + my patch
> 
> Messaging: 47.374
> Pipe: 113691.199

I did not get the email with your original patch,
either to my inbox or my lkml folder, but I saw the
patch on pastebin, and it looks good.

When you resend it, please feel free to add my

Acked-by: Rik van Riel <riel@...hat.com>

Assuming the version you meant to email yesterday was
the same one that you showed me on pastebin, of course :)
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